- Hormonal therapy: Patients who develop breast cancer while receiving a selective estrogen-receptor modulator (SERM; e.g., tamoxifen, toremifene, raloxifene) or an aromatase inhibitor (e.g., anastrazole, letrozole, exemestane) for breast cancer prevention or a SERM for other indications (e.g., raloxifene for osteoporosis) are not eligible; however, patients may have received up to 8 weeks of a SERM or aromatase inhibitor for this malignancy and still be eligible for study entry